The present invention relates to a novel composition for plant growth regulation and specifically provides certain 1-(hydrocarbylcarbamoly)-3-(carboxy or hydrocarbyloxycarbonyl)-isoureas and isothioureas and the lactams of the 3-carboxy compounds (which are triazine derivatives) for use in association with one or more gibberellins for the regulation of plant growth.
"Gibberellin" is a generic name for a series of natural plant hormones which act as accelerators of the growth of higher plants. The gibberellins were first discovered as the metabolic products of the soilborne fungus, Gibberella fujikuroi, which causes a disease of rice seedlings manifested in the tall growth of infected plants. A series of related compounds identified as gibberellin A.sub.1 through A.sub.44 has been discovered and the various compounds isolated; the gibberellins have been found in the culture broth of Gibberella fujikuroi and in various higher plants including certain beans. At present the giberellins are used for the acceleration or regulation of various stages of plant development, particularly growth, efflorescence, germination and parthenocarpy, particularly of the true grasses of the order Graminae, flowering plants, vegetables, fruit trees and other trees. The main component of the gibberellins used in practice is gibberellin A.sub.3, otherwise known as gibberellic acid.
The gibberellins have, therefore, a variety of useful functions. However, their use is greatly limited by their expense and insufficient effectiveness at low concentrations. As a result, research has concentrated on an effort to find a synergistic agent which can be used to enhance the activity of the gibberellins. Few synergistic agents have, however, been discovered and fewer still have been put to practical use.
There is, therefore, an urgent need for synergistic agents for use with the gibberellins.